That's the least he could say. I mean, Mangini appreciates Portnoy a lot and absolutely admires him, and as Petrucci himself said on The Spirit Carries On documentary, they had played with both Mangini and Portnoy on stage before, surely because of Portnoy as he was the one who enjoyed doing that type of stuff and was the one with those ideas. Mangini and Portnoy even went to Berklee together, iirc. After having Mangini say that he loves Portnoy's drumming and that they're friends, I think that's what Portnoy should have said.
In any case, I wonder if Mangini has talked with Portnoy ever since he became the new drummer...